Nutrient Pollution and the Challenge of Manure Management 

Manure can be a valuable resource for agriculture, helping recycle nutrients, build soil health, and support crop productivity. With more than 1.4 billion tons generated annually in the U.S., managing manure sustainably is an important and complex challenge—particularly in regions where manure produced exceeds local fertilizer demand. When nutrients from manure are not fully absorbed by crops or soils, they can leach into groundwater or run off into waterways, where they may contribute to local environmental and public health concerns.

We’re here to explore the current evidence around nutrient pollution, its underlying drivers, and its potential consequences. Vaulted cares about nutrient pollution and manure management because we aim to drive the greatest possible impact from our operations—this means finding and utilizing the manure that isn’t being used productively today, or is contributing to excess nutrients in the local environment. 

Manure can support crop growth and maintains soil health 

Manure is used to fertilize approximately 8% of the 240 million acres of cropland in the U.S. It supports yields and soil quality through a range of mechanisms: 

• Increasing soil nutrient levels (nitrogen, phosphorus, potassium) 
  
• Enhancing microbial activity and nutrient cycling 
  
• Improving soil structure, filtration, and water uptake 
  
• Preventing erosion through better soil stability 

Cropland with ideal manure application can achieve similar yields to those using only synthetic fertilizers.

Matching nutrient supply and demand is challenging 

Manure is most effective when applied at the “agronomic rate”—the level of nutrients that soil and plants can effectively absorb. Two systemic factors often make this difficult: 

1. Geographic mismatch: Livestock operations in the U.S. are concentrated in specific regions, generating more manure than local croplands can absorb. A USDA study found that 60% of manure nitrogen and 70% of manure phosphorus are produced in areas where there isn’t enough land to apply it sustainably. . Since manure is bulky and contains fewer nutrients per ton than synthetic alternatives, it’s usually not practical—or affordable—to redistribute it far from where it’s produced.
   
   
2. Nutrient variability: Manure nutrient content varies by source and storage method. The release of nutrients from manure, especially nitrogen, can also be slow and out of synch with specific crop needs. In the absence of precise data, farmers may apply more than necessary to ensure crops receive adequate nutrition or continue using synthetic fertilizers in high quantities.A 2018 national survey found only 44% of corn farmers reduced their use of synthetic fertilizer when applying manure, and among them, the average reduction was only 46%.

Excess manure impacts drinking water quality and ecosystems 

When nutrients exceed crop uptake and soil retention, they can enter groundwater and surface waters. According to the EPA’s National Rivers and Streams Assessment, more than 40% of river and stream miles in the U.S. have elevated nitrogen and phosphorus levels, with animal manure and synthetic fertilizers as two of the leading causes. 

This nutrient pollution can contribute to: 

• Drinking water contamination: Elevated nitrate levels in water has been linked to higher risks of colorectal, thyroid, breast, and bladder cancer. 
  
• Ecosystem disruptions: Excess nutrients can trigger algal blooms and create hypoxic “dead zones.” A Florida study found that 64% of over 600 fish kill events were associated with oxygen-depleted waters linked to excess nutrients. 
  
• Higher water treatment costs: In communities with excess nitrates, installing nitrate removal systems can significantly raise drinking water costs. A study from Iowa State University estimated that nitrate removal systems could increase public water treatment costs from $0.05–$0.10 per gallon to $0.22–$4.60 per gallon depending on the treatment method and community size. 

Nutrient pollution is a national problem with regional hotpots 

While nutrient pollution is a national issue, its severity varies by region. Phosphorus levels are considered “poor” in over a third of stream miles across 8 of 9 U.S. regions. The Midwest and Plains regions most often face issues of excess nitrates in groundwater due to shallow aquifers and intensive agriculture. However, nitrate levels in drinking water also routinely exceed EPA standards in the East Coast, Pacific Northwest, and California based on a recent EPA analysis. 

 Source: Pennino et al. 2020 

There are more than 500 “dead zones” globally—areas with critically low oxygen levels that make them uninhabitable for most marine life. Excess nutrients produced in agriculture-intensive regions collect in major watersheds and have massive impacts on coastal ecosystems. In the US, the two largest and most economically costly are located in the Gulf Coast and the Chesapeake Bay. 

In the Gulf Coast, a hypoxic zone over 6,000 square miles—roughly the size of Hawaii—forms each year, primarily from nutrient runoff along the Mississippi River. Algal blooms and fish kill events can reduce commercial fishing and tourism activity across the East Coast and Gulf Coast. Two-fifths of US seafood comes from the Gulf region, and the Gulf Coast dead zone generates estimated annual losses of over $80 million to the commercial fishing industry. 

Despite notable progress in the Chesapeake Bay, over 100 million pounds of nitrogen still enter the Bay annually. In some areas like the Susquehanna River Basin, up to 60% of private wells exceed nitrate safety limits. Nutrient management programs have helped reduce the Bay’s dead zone by 40% from its 40-year average as of 2023. 

Looking ahead 

Nutrient pollution often stems from logistical and geographic mismatches—not from how farmers or waste managers are doing their jobs. In areas where manure exceeds local demand or application capacity, new approaches are needed to improve ecosystem and public health outcomes. Addressing the scale and complexity of nutrient pollution will require sustained collaboration and innovation across policy, technology, and agricultural systems. Vaulted is one part of the solution by taking excess manure that can’t be productively used and locking it away deep underground, where it doesn’t add to the nutrient pollution problem. We’re working with municipalities and farmers to tackle these challenges today.